State the Changes in the Position, Size and Nature of the Image of an Object When Brought from Infinity up to a Concave Lens. Illustrate Your Answer by Drawing Ray Diagrams. - Physics


State the changes in the position, size and nature of the image of an object when brought from infinity up to a concave lens. Illustrate your answer by drawing ray diagrams.



(i) When object (AB) is situated at infinity then parallel rays from object appears to fall on concave lens. Due to which image forms at focus. This image is highly diminished in size and virtual and upright 

(ii) When object (AB) is situated at any point between infinity and optical centre of the lens then image forms between focus and optical centre. This image is diminished in size and virtual and upright.


Concept: Concave Lens
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Chapter 5: Refraction through a Lens - Exercise 5 (B) 1 [Page 121]


Selina Concise Physics Class 10 ICSE
Chapter 5 Refraction through a Lens
Exercise 5 (B) 1 | Q 28 | Page 121


If the numerical value of the power of this lens is 10 D, what is its focal length in the Cartesian system ? 

Where must the object be placed for the image formed by a converging lens to be: 

 real, inverted and same size as the object? 

 How would you alter the above diagram to show how a converging lens can produce a beam of parallel rays of light. 

Fill in the following blank with suitable word: 

 A convex lens .................. rays of light, whereas a concave lens .................. rays of light. 

Give the position, size and nature of image of formed by a concave lens when the object is placed:
 anywhere between optical centre and infinity.

 State one practical use each of convex mirror, concave mirror, convex lens and concave lens.

When an object is placed 10 cm in front of lens A, the image is real, inverted, magnified and formed at a great distance. When the same object is placed 10 cm in front of lens B, the image formed is real, inverted and same size as the object. 

 What is the nature of lens A?

A person finds difficulty in seeing nearby objects clearly. His vision can be corrected by using spectacles containing:
(a) converging lenses
(b) diverging lenses
(c) prismatic lenses
(d) chromatic lenses

Out of the two lenses, one concave and the other convex, state which one will show the divergent action on a light beam.

How does the action of a convex lens differ from that of a concave lens on a parallel beam of light incident on them? Draw diagram to illustrate your answer.

State two applications  a concave lens .

Explain the working of an astronomical telescope using refraction of light.


A student obtained clear image of window grills on the screen. But the teacher told him to get the image of a tree far away, instead of window. To get a clear image,  the lens must be ............................

 Express power of a concave lens of focal length 50 cm with its sign.

Which lens is converging:

A concavo-convex lens or a convexo-concave lens?

A lens always forms an image between the object and the lens. 

name the lens.

A concave lens forms the image of an object kept at a distance 20 cm in front of it, at a distance 10 cm on the side of the object.

What is the nature of the image?

Find the focal length of the lens.

A concave lens is a focal length 30 cm. Find the position and magnification (m) of image for an object placed in front of it at distance 30 cm.State whether the image is real on virtual?

Choose the correct alternative and rewrite the following: 

Inside water, an air bubble behaves ....................

An object is placed at a distance of 60 cm from a concave lens of focal length 30 cm.
(i) Use the lens formula to find the distance of the image from the lens.
(ii) List four characteristics of the image (nature, position, size, erect/inverted) formed by the lens in this case.
(iii) Draw a ray diagram to justify your answer of the part (ii).

When an object is kept within the focus of a concave mirror, an enlarged image is formed behind the mirror. This image is :

An object is placed in front of a lens between its optical centre and focus. The formed image is virtual, erect, and diminished. Name the lens used.

Draw images in case of a concave lens when the object is at any point on the principal axis between the lens and infinity.

Convex lens : converging : : concave lens : _______

Convex magnifying glass is called divergent magnifying glass and concave magnifying glass is called converging magnifying glass.

Distinguish between Concave lens and Convex Lens.

Distinguish between:

Concave Lens and Convex Lens


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